power predictions method

Hallo

I will design an approximately 70 x 30 meters roro catamaran with wawe piercing hulls. Do You have any ideas if there is any appropriate resistance prediction methodes (semi empirical) for that kind of vessels. I guess that Holtrop and Mennens method not will do the work

brgds

C-J

 

No, Holtrop and Mennon won't go anywhere near a catamaran, especially a wave piercer. AF Molland's work on Catamarans may be of more use, but I think fairly extensive tank testing would be highly advisable.

Tank testing will also give a good insight into the sea-keeping abilities, and (with the right model) sea-keeping in flooded conditions.

These vessels are quite hard to design, approach the problem carefully,

Tim B.

 

test with michlet program i test it on big vessel (with bulb and trim wedge)and i have very good results on bare hull i compare with towing tank test and it'very good for 80% of hulls (include pods design hull)

french 44

 

Michelet is a good option for resistance prediction in slim displacement hulls; it will also calculate interference drag in a multihull. Your individual hulls must have length/beam ratios of 6 or more to get good results from it, and should operate at a subcritical Froude number (full displacement hulls work best). It will not do any stability or trim calculations for you, but will give pretty good resistance and power curves. I agree with Tim that if you intend to actually build this vessel, you will need to do a lot of tank testing; I would include tank testing with appropriately scaled waves as well.

 

hey, I may help you. I now own the Auto power software. But you must provide me more characteristic of the hull. The best way is to give me your lines plan.

My email is cuongshipdesign@yahoo.com
Best regard

 

That wolud be very nice, I email You the linedrawings in a couple of days.
Which file format do You want?

 

Its pity that, we naval Architects are lagging behind latest scientific advancement. We are still dependent on empirical relations, statistical data from series of model tests in 1970s-80s. CFD methods are still in their transformation state to produce reliable results & common usage!